We stayed at SoOne for a week – and we definitely see us staying there for a month or two.
First of all, location is great. It is secluded, but 5 minutes and you are on Silom Road, where you can get anything your soul desires. There are three 7-11 in 5 minute reach and Tops supermarket if you want something extra. Local restaurants are great (if you want recommendations – "Day to Night", "Mama Mia" and "Bonita" are all great).
The apartment is little, but doesn't feel tight. It has refillable shampoo and shower gel – kudos to the host! Mini-kitchen works well. Bed was ok, with pretty hard mattress, which is usually good for back. Overall our time was great.
The only thing to have in mind: window view is building across and audibility of neighbours can be a little too good (: But if they respect night times, it won't be any trouble – at most minor discomfort if you are accustomed to good noise-isolation.
Sending my great appreciation to host, it is a great place for a great price!